Outboard propeller mechanisms for vessels such as barges, scows and the like are old in the art and as illustrated, for example, in U.S. Pat. Nos. 2,335,597; 2,458,813; and 2,902,967. In these patents, a power plant is mounted in a stationary position on the vessel with its drive shaft parallel to the longitudinal axis of the vessel, and the propeller assembly is mounted so as to be rotatable about a horizontal axis athwartship of the vessel to enable disposing the propeller in a perpendicular position extending downwardly into the water and while in position to rotate the propeller about a vertical axis for the purpose of steering and also to enable swinging the entire propeller assembly upwardly to withdraw it from the water. The driving connection for the power plant to the outboard propeller assembly, because of the right angular relation of the drive shaft to the input shaft, imposes limitations on the drive angles, limits the input horsepower and speed, occupies more space than is desirable, transmits shock loads and generally is a source of constant trouble. It is the purpose of this invention to simplify the drive between the power plant and the outboard propeller assembly in such a way as to enable economizing in space requirements and to enable complete freedom of movement of the propeller assembly without interfering with the continuity of drive between the power plant and the propeller assembly.